1) RED SKY AT NIGHT… means that as the sun sets in the west, if it has a red hue or color to it, then the moisture was further west of their location. Thus SAILORS DELIGHT. A beautiful sunset.

2) RED SKY IN MORN…means that as the sunlight from the rising sun passes through moisture, it too will be red. This means that with the rotation of the earth, this will bring this moisture (and possible storm) right on top of them and it is only a few hours away. SO SAILORS TAKE WARN."I hope this bit of weather science helps.